Easy opening beverage containers are well known in the beverage industry. Typically, a beverage container comprises a body and a separate can end or lid formed of an aluminum sheet--typically 0.011" (0.28 mm) to 0.013" (0.33 mm) thick. A conventional can lid may employ one of several pull-type tabs. A popular type of lid has a tab that is attached to a top plate by a rivet to form a lever. To open the can, a user lifts one end of the tab to urge the other end downward against a tongue or tear panel formed by a score in the top plate. The tab member forces the tongue downward until the score pattern ruptures. The score may be discontinuous to form a hinge area that connects the tongue to the top plate, even after opening.
A common operation for forming a can end having a tongue defined by a score pattern comprises the step of placing a metal material between a score die and mating anvil. Thereafter, the score die is brought down upon the metal material with a force sufficient to depress the metal material to form the score pattern.
Ease of opening and enhanced strength of the lid components are long standing goals of designers and researchers. For example, U.S. Pat. No. 5,653,355 to Tominaga et al. ("Tominaga") discloses a can lid having a top plate, a tab, a tongue formed by a score, and a hinge area formed in the lid. However, the lid disclosed in the Tominaga patent has several drawbacks. First, the top plate has a center which is a fulcrum point. Such a layout may not be desired in light of tongue size and location, tab length, aesthetics, strength characteristics, and like variables.
Second, the Tominaga patent discloses that the force application point, the fulcrum point, the tab nose, and the depression force point form a straight line. Such an alignment restricts the depression force point to a location that is not optimum with respect to the opening characteristics. Third, the Tominaga patent discloses a recess that is disposed beneath the tab nose having a straight side perpendicular to the straight line as defined above. The straight side yields to an arcuate side generally to form a D-shaped recess. This D-shape inherently requires a large surface area in the critical tongue area, within which space should be conserved, and might position a stress riser at a problematic location. Fourth, a large deboss in the top plate of the Tominaga patent contains and is disposed outside of the score area and tab, which has inherent drawbacks, especially with respect to the score. Furthermore, like many can lid designs, the lid disclosed in the Tominaga patent may be prone to loose metal or excess metal in the tongue area, and may generally not provide optimum accessibility to the finger of the user (that is, mechanical and geometrical characteristics of the tab with respect to the tongue and the top plate).
The present invention is directed to the goals of improving the opening considerations of pull type tabs, as well as possessing other attributes that will be apparent to persons familiar with such technology.